sumpsimus
Adherence to or persistence in using a strictly correct term in rejection of a more common (but technically incorrect) form.
countable, uncountable
I'll not change my old mumpsimus for your new sumpsimus!
A person obstinate or zealous about such correctness; a pedant.
countable, uncountable
Where it comes from
From Latin sumpsimus, c. 1540–50. See mumpsimus for details.
Adapted from the Wiktionary entry sumpsimus (CC BY-SA 4.0).